Abstract: In order to improve the anti-noise performance of particle detection experiment, this paper improves the Chahine algorithm, introduces one-dimensional smooth function. This paper focuses on the analysis of the principle of Mie scattering, calculates the extinction coefficient matrix. This paper establishes soft sensor model of the particle size distribution and measures light extinction data at multi wavelengths to obtain the particle size distribution curve of the particle system. Different degrees of noise are added to compare and prove that Chahine algorithm has strong anti-noise ability, the accuracy of the experimental results is higher.